Atomaria groehni, Perkovsky et Lyubarsky, 2014

Lyubarsky, G. Yu. & Perkovsky, E. E., 2021, New findings of Cryptophagidae (Coleoptera: Clavicornia) from Baltic amber in the unbiased collection of the Paleontological Institute of RAS, Russian Entomological Journal 30 (3), pp. 282-287 : 283-286

A. groehni Perkovsky et Lyubarsky, 2014 Figs 5–6 .

MATERIAL. PIN 964/1325, Baltic amber, Late Eocene. Specimen is deposited in the amber collection of the PIN RAS. Sex: unknown.

RE-DESCRIPTION. Length of body 1.0– 1.1 mm, body elongate ( Figs 5–6 ), moderately arched, head, pronotum, and elytra light-brown.Elytra slightly convex, covered with slightly curved long elevated pubescence.

Head transverse, of normal size, with hemispherical facetted eyes, strongly punctured. Antennae moderately long, with club reaching beyond base of pronotum, flagellomeres slightly elongate, antennomeres 1 st, 2 nd about 1.5 times as long as broad, 3 rd slightly elongate, 4 th and 6 th antennomeres as long as broad, 5 th 1.5 times as long as broad, 7 th, 8 th subquadrate, 9 th slightly transverse, 10 th strongly transverse, 11 th obliquely oval, antennomeres 9–11 equal in width. Antennae inserted under the lateral margin of the forehead, widely separated basally, antennal insertions close to the eyes.

Pronotum convex, not narrowed basally, slightly transverse, 1.2–1.5 times broader than long, broadest before the middle, moderately strongly and very densely punctured (distance between punctures equal to their diameter), a single puncture smaller than the diameter of the eye facet. Pubescence long and elevated. Sides finely margined, anterior edge weakly sinuate, without excision. Pronotum broadest before middle of its length. Side borders visible from above along the entire length. Lateral margin without callosity. Posterior corners right angled, basal edge lobed, strongly sinuate, basal groove shallow.

Scutellum small, transverse. Elytra short-oval, moderately convex, humeral corners rounded, maximum breadth of elytra in first third of their length, 1.6–1.7 times as long as wide and 2.5–2.7 times as long as thorax, punctuation slightly stronger and sparser than that on pronotum. Punctures in the basal part slightly stronger than those on the pronotal disk, and approximately 1.5–2 diameters apart from their lateral neighbours on an average; humeri not toothed.

REMARKS. Representatives of Atomaria are found in all biogeographic realms including 127 species in the Palaearctic Region [ Johnson et al., 2007].

Atomaria groehni differs from similar species with lateral margin of pronotum visible from above, such as A. morio Kolenati, 1846 and A. versicolor Erichson, 1846 , by small size and long elevated pubescence. A. groehni differs from species similar to A. testacea Stephens, 1830 in pronotum slightly narrowed basally and small size. A. groehni differs from most species of the genus in the structure of the antenna: the segments of the flagellum are subquadrate or slightly elongate.

Among the species of amber, it differs in a combination of characters: pronotum broadest before the middle of its length; elytra covered by long elevated pubescence; side borders of pronotum visible from above along the entire length.

Figures

Figs 5–6. Photo of a new specimen of A. groehni from Baltic amber: 5 — dorsal view; 6 — dorsolateral view. Рис. 5–6. ВнеШний вид A. groehni иЗ балтийского ЯнтарЯ: 5 — сверху; 6 — сверху и сбоку.